AbstractObjectivesThe use of headgear is a controversial issue in girls’ lacrosse. We compared concussion rates among high school lacrosse players wearing versus not wearing lacrosse headgear.MethodsStudy participants included a sample of convenience of high schools with girls’ lacrosse from across the United States. Certified athletic trainers reported athlete exposure and injury data via the National Athletic Treatment, Injury and Outcomes Network during the 2019 through 2021 seasons. The Headgear cohort was inclusive of high schools from the state of Florida, which mandate the use of ASTM standard F3137 headgear, while the Non-Headgear cohort was inclusive of the remaining states, none of which have headgear mandates. Incidence Rate Ratios (IRR) and 95% Confidence Intervals (CI) were calculated. IRRs with corresponding CIs that excluded 1.00 were deemed statistically significant.Results141 concussions (Headgear: 25; Non-Headgear: 116) and 357,225 Athlete Exposures (AE) were reported (Headgear: 91,074AE; Non-Headgear: 266,151AE) across all games and practices. Overall, the concussion injury rate per 1000AE was significantly higher in the Non-Headgear cohort (0.44) than the Headgear Cohort (0.27) (IRR=1.59, 95% CI:1.03 - 2.45). The IRR was significantly higher for the Non-Headgear cohort during games (1.74, 95% CI: 1.00, 3.02) but not for practices (1.42, 95% CI: 0.71, 2.83).ConclusionsThese findings indicate that concussion rates among high school girls’ lacrosse players not wearing headgear were 59% higher than those wearing headgear. These data support the use of protective headgear to reduce the risk of concussion among high school female lacrosse athletes.SummaryWhat are the new findingsThe use of lacrosse headgear meeting the ASTM F3137 standard was associated with a lower risk of experiencing a concussion injury among high school girls’ lacrosse players.How might these findings impact clinical practice in the future?Lacrosse headgear may be warranted for use for concussion risk mitigation among high school girls’ lacrosse players.Lacrosse headgear may be considered for concussion risk mitigation at other levels of play such as the youth or collegiate levels; further study is warranted.